Vaso-occlusive devices are surgical implements or implants that are placed within some opening in the human body. Typically the opening is either within the vasculature or some other region which is to be occluded. Such other sites include fallopian tubes and bile ducts. They are delivered typically via a catheter. It is intended that the devices either block the flow of blood through a vessel making up that portion of the vasculature via the formation of an embolus. An embolus may also be formed within an aneurysm stemming from a normal vessel by use of this invention.
One such widely used device is the helically wound vaso-occlusive coil. Many such coils are dimensioned to engage the walls of the vessels or other sites they are intended to occlude. Other significantly less stif helically wound devices have also been described in the literature.
A patent describing an early vaso-occlusive device which patent, parenthetically, also provides an excellent background to the vaso-occlusive technology at that time is Ritchart et al. (U.S. Pat. No. 4,994,069). Ritchart et al. describes a vaso-occlusive coil that assumes a linear helical configuration when stretched and a folded, convoluted configuration when released from the catheter. The stretched condition is used in placing the coil at the desired site via passage through the catheter. The coil assumes a relaxed configuration--which is better suited to occlude the vessel--once the device is released from the catheter. Ritchart et al describes a variety of secondary shapes including "flower" shapes and double vortices.
The use of vaso-occlusive coils having attached fibrous elements in a variety of secondary shapes is shown in Chee et al. (U.S. Pat. No. 5, 304,194). Chee et al. describes a helically wound device having a secondary shape in which the fibrous elements extend in a sinusoidal fashion down the length of the coil. These coils, as with the Ritchart et al. coils, are produced in such a way that they will pass through the lumen of a catheter in a generally straight configuration and, when released from the catheter, form a relaxed or secondary shape in the lumen or cavity chosen within the human body. The fibrous elements shown in Chee et al. enhance the ability of the coil to fill space within the vasculature and to facilitate formation of an embolus and subsequent allied tissue.
There are a variety of ways of placing shaped and linear coils into the human vasculature. In addition to those patents which are believed to describe only the physical pushing of a coil out into the vasculature, (e.g., Ritchart et al.), there are a number of other ways to release a coil at a specifically chosen time and site. For instance, U.S. Pat. Nos. 5,354,295 and its parent 5,122,136, both to Guglielmi et al. describe a device which is electrolytically detachable from its pusher wire.
A variety of mechanically detachable devices is also known. For instance, U.S. Pat. No. 5,234,437, to Sepetka, shows a coil which is helically unwound from a pusher having an interlocking surface. U.S. Pat. No. 5,250,071, to Palermo, shows an embolic coil assembly using interlocking clasps mounted both on the pusher and on the embolic coil. U.S. Pat. No. 5,261,916, to Engelson, shows a detachable pusher-vaso-occlusive coil assembly having an interlock ball and keyway-type coupling. U.S. Pat. No. 5,304,195, to Twyford et al., shows a pusher-vaso-occlusive coil assembly having an affixed, proximally extending wire carrying a ball on its proximal end and a pusher having a similar end. The two ends are interlocked and disengage when the coil is ejected from the distal end of the catheter. U.S. Pat. No. 5,312,415, to Palermo, shows a multiple coil device in which the coils are placed on a single pusher in the form of a guidewire which has a section capable of interconnecting with the interior of the helically wound coil. U.S. Pat. No. 5,350,397, to Palermo et al., shows a pusher having a throat at its distal end and a pusher through its axis. The pusher sheath will hold onto the end of an embolic coil and the embolic coil will then be released upon pushing of the axially placed pusher wire against the proximal portion of the vaso-occlusive coil.
Vaso-occlusive coils having little or no inherent secondary shape have also been described. For instance, in U.S. patent application Ser. No. 07/978,320, filed on Nov. 18, 1992, entitled "Ultrasoft Embolism Coils With Fluid-Like Properties" by Berenstein et al. is coil having little or no shape after introduction into the vascular space.
A variety of other patent applications assigned to Target Therapeutics, Inc., of Fremont, Calif. describe coils or other related vaso-occlusive devices having specific shapes. Of particular interest is U.S. design patent application Ser. No. 29/037,001 filed Mar. 31, 1995 for spiral vaso-occlusive coils by Mariant et al.
None of these previously-described devices or self-forming helically wound coils which self-form into secondary structures having opposing conical end separated by a generally cylindrical portion between those opposing ends.